Baby
Signing:

A study funded and supported by the National Institutes of Health in
2000 found that signing helps babies learn to talk.
Children who had been instructed in signing had an
advantage over non-signing children in language
development. Children who are taught to sign
demonstrate intellectual advantages. At 8 years,
children were found to have IQs on average 12 points
higher than those who had not been exposed to
signing as a baby (Bevinetto Feld, 2004).
Researchers speculate that the IQ advantage
associated with signing might be the result of
jump-starting a baby's intellectual development. It
is also possible that the social and emotional
benefits of signing, such as higher self-confidence,
can have long-term effects on IQ (Ulene, 2006).